Some customers of our René Herse cranks have noticed that their brand-new cranks show traces of having been mounted on a bottom bracket. Did they receive used cranks by accident? No, the cranks are brand-new.

As part of our quality control, we mount each crank, with the chainrings the customer ordered, on a bottom bracket. We want to make sure that the chainrings don’t wobble. Our tolerances for chainring “runout” are tighter than most in the industry, but when you have a flexible frame, the frame flex and runout of the chainrings can add up. Having your chain rub on the front derailleur can be annoying.

In making the new René Herse cranks, we found out why this design has not been copied more widely. It offers many advantages over other cranks, but it is much harder to make. Conventional cranks have a large bolt-circle diameter and four or five beefy arms, so you can pull even a slightly out-of-round chainring into shape. With three lightweight arms and a small bolt-circle diameter, very small irregularities are translated into a noticeable wobble on the outside edge of the chainring. Thus, the manufacturing tolerances have to be much more precise. To make sure that every crank meets our standards, we check it after it is assembled. Then we send the new cranks to the customer.

100% quality control used to be common among high-end makers. In the days when Campagnolo still gave a lifetime warranty on their products, they also mounted every crank before it left the factory. Mike Kone, who used to own Bicycle Classics and who has handled more “New Old Stock” Campagnolo parts than almost anybody, noticed mounting traces on every “NOS” Campagnolo Nuovo and Super Record crank.

Today, many companies leave the quality control to their customers. If something is not up to standards, the customer can return it for a free replacement. That is a lot cheaper than actually checking your products. And since not every customer will send back a sub-standard product, you have fewer rejects.

When we design our products and check their quality, I often ask myself the question: “What would René Herse have done?” Herse was known as a perfectionist. He did not send out a product without being sure that it performed as intended. It is our goal to live up to his standards.

16 Responses to 100% Quality Control

Very interesting. All the little things one forgets about until you have to do it yourself. Reminds me of my first attempt building a wheel, I’d never thought about it before then, but suddenly occurred to me, “well, how true is true?”

So, the obvious question… what are your tolerances? Do you mind sharing? Do you know how they compare to industry norms?

Sounds like industry might be as long as it looks round, unless a customer complains.

Interesting. Many manufacturers use statistical process control as an effective alternative to 100% inspection. Can you rework the chain rings if they exceed your standard for run out? What sort of tolerances can we expect when we purchase a new crank?

A statistical inspection is great, if you are willing to accept that you miss some. We check each crankarm with a known, very true chainring. We also check each chainring on a fixture. Then we mount the crank and check it again. This makes sure that the tolerances of crankarm and chainring don’t reinforce each other in a negative way. (Everything has a tolerance, and if the tolerances of chainrings and crankarm spider add up in a bad way, you’ll have more runout than is acceptable.)

Our chainrings are made from 7075 aluminum, because that material is far more durable than the more common 6000-series aluminum that was used by most makers in the old days (and many small makers today). 7075 does not bend, so you cannot rework the chainrings if they have too much runout. You could try and bend the crankarm spider to compensate for it, but if you ever replaced the chainrings, you’d have a larger problem than before.

The exact tolerances are proprietary for a variety of reasons. I don’t think you will be disappointed by the cranks… As for the tolerances of the rest of the industry, we measured a lot of cranks to determine the actual tolerances (rather than the design tolerances, which aren’t always met).

Constructed correctly, a statistical sampling QC system can catch as many or more defects as checking every unit, since you also have a margin for error when checking every unit (maybe more due to fatigue or other mistakes), and a well-constructed statistical sample can reduce the margin for error at least as low as one defined as measuring every unit. There’s no such thing as 100% accurate QC, only ones with greater or lesser error counts.

We do the final quality check as the orders come in – we assemble each crankset to order, since there are so many chainring choices. So there is little risk of getting tired and letting the 100th crankset slip through – since we rarely check more than 2 or 3 at a time.

I really like this Rene Herse man for his principles and pride. Rest in peace.
Following his principles is also very astute business practices, especially for those who appreciate absolute quality first time. It takes the same effort to make something right as wrong and getting it right the first time for your customer will further bring customers.

As someone who appreciates and uses finely manufactured bicycle components (vintage campy!) I must say that I find your approach refreshing. I recently bought the 50.4 bcd cranks from Velo Orange and, upon receiving them, was immediately disappointed with the over all feel and build quality. I mounted and used them but the side to side wobble or “runout” was absolutely horrible making them not only difficult to setup but they ride something like bio pace chain rings which, incidentally, I was trying to replace. I should have tried yours. I would gladly pay more for something of outstanding quality. I have yet to see, touch or try these lovely looking cranks but you have already restored some of my confidence through your thoughtfulness to manufacturing and cycling in general. Thank-you.

A bit off topic, but I’m more concerned with chainring runout of the kind whereby the distance from the center of the spindle hole to the teeth varies. This is a problem only for those running single speed setups (fixed or freewheel) or internally geared hubs because it leads to varying chain tension as the out of true chainring rotates through its “wide” and “short” cycles. Imagine a Biopace chainring albeit on a smaller scale. Of course, this is not really a problem with derailleur-equipped bikes as the tension is kept constant by the mechanism. Jan, do you inspect your chainrings for this kind of runout?

I read your articles and I pinch myself to make sure I’m really reading it! You seem to be hitting the nail on the head, whatever the topic, with a surgical precision every time. It must have taken lots of practice and insight to deal with a subject this way. And it’s so refreshing a feeling for me to meet a person, be it on another continent, who simply does things well. But to the point.

A year ago when I didn’t even know people like you and the kind who read your blog existed at all I bought a city bike with a hub gear. Up till then, childhood aside, I had only ridden bikes with derailleurs so when my bike dropped a chain time after time my search led to a wobbly chain-ring. When I proudly shared my discovery with the manager of my LBS (where the bike had unwarely been purchased) naturally hoping for a replacement he, to my utter surprise, just ran me down, “Don’t you know that chain–rings are never round?” ”What? Chain -rings are never round?” it was my turn to be surprised now. I took my bike and left the shop to start looking for the answers.

A year has gone and there are times when I can’t get my hands clean – a testimony to my successful tinkering with my bikes (e.g. a pair of aluminum fenders back on where they belong ..-:) and reading blogs like yours and equally useful comments by the readers.

You are right, we don’t always think about how “round” and “straight” both are ideals that can be approximated with varying degrees of success. Ball bearings are very round, but even ball bearings come in different grades based on how round (and how similar to one another) they really are.

It’s great that you check each crank with it’s chain rings before you ship them. Also each chain ring independently. What happens if a customer orders a replacement chain ring with tolerances that reinforce those in his or her crank set in a negative way? I guess one could try rotating the chain ring to see if one mounting orientation is better than the others.

I once tried to mount a Pro 5 vis chain ring to a post 2007 TA crank. the drilling tolerances were so poor I could only mount it in one orientation. I never had this problem with the same chain ring on a sugino Px, or older TA crank.

First, we make our rings from 7075 aluminum, so they will last a very long time. When I rode on Campagnolo cranks with chainrings from the same material, I usually got at least 30,000 miles out of the rings. If a customer, years from now, gets a replacement chainring that doesn’t spin as round as we’d like, we’ll send him a new one. We take customer service seriously.

TA’s products are wonderful, but their tolerances aren’t always as tight as one would like. You could file the holes slightly to make it work in any orientation.